Fractional Flow Reserve Results Research Articles

Comparison of Nitroglycerin-Induced Pressure Ratio Drop and Resting Full-Cycle Ratio in a Pressure Wire Study.

Background/Objectives: The acute drop in distal coronary pressure (Pd)-to-aortic pressure (Pa) ratio after intracoronary nitroglycerin (NTG-Pd/Pa) administration is an acceptable estimate of fractional flow reserve (FFR). We aimed to compare the diagnostic performance of NTG-Pd/Pa with that of the resting full-cycle ratio (RFR) in predicting the binary results of FFR. Methods: This study included two prospective studies registered under the numbers NCT04700397 and NCT03693157. Altogether, 202 vessels were included. The optimal cutoff of NTG-Pd/Pa for predicting FFR ≤ 0.8 was identified and validated in another prospective registry. We used the McNemar's test and the DeLong method to compare the diagnostic efficiency of NTG-Pd/Pa vs. RFR in predicting FFR ≤ 0.8 in a pooled cohort. Results: NTG-Pd/Pa was strongly correlated with FFR (r = 0.945, p < 0.001). The NTG-Pd/Pa cutoff for predicting FFR ≤ 0.8 was 0.85 in both the derivation and validation cohorts. The area under the receiver-operating characteristic curve (AUC) and accuracy in predicting FFR ≤ 0.8 were higher for NTG-Pd/Pa than for RFR in the pooled cohort (AUC 0.97 vs. 0.91, p < 0.001; accuracy 91% vs. 84%, p < 0.001). The sensitivity and negative predictive values were also higher for NTG-Pd/Pa than for RFR (all p < 0.05). The specificity and positive predictive value were numerically higher for NTG-Pd/Pa than for RFR (all p > 0.05). Conclusions: The diagnostic performance of NTG-Pd/Pa may surpass that of the RFR in predicting the binary results of the FFR.

Single centre experience using vessel Fractional Flow Reserve (vFFR) and diagnostic performance compared with invasive Fractional Flow Reserve (FFR)

Abstract Background Fractional flow reserve (FFR) is a diagnostic gold standard in the functional assessment of coronary artery stenoses (1). Alternative invasive and non-invasive methods have been developed in an attempt to avoid limitations associated with FFR including added procedural risk, patient discomfort, time and cost. Vessel fractional flow reserve (vFFR) is a novel software using two angiographic projections to generate a 3D vessel reconstruction which has shown high diagnostic accuracy in predicting a positive FFR (2-4). Methods All patients undergoing coronary angiography between 01/10/2022 and 08/03/2023, where FFR was performed, were assessed. Patients were included where images met requirements necessary to use vFFR software. vFFR measurements were taken retrospectively by a single investigator and not used to inform patient care. Data were expressed as mean +/- standard deviation and %. The correlation of vFFR to FFR was compared using Pearson’s correlation coefficient. Receiving operator characteristic (ROC) area under the curve (AUC) analysis was used to determine diagnostic performance. Statistical analysis was performed using SPSS v27. Results 28 of 37 patients and 32 of 44 vessels were included and analysed with vFFR software. Excluded vessels were unsuitable due to insufficient frame rate or projection angulation during angiography. Mean age was 63 +/- 3.8 years and 75% of patients were male. Of 32 vessels assessed, 20 were LAD, 5 RCA, 5 LCx and 2 LMS. 29 of 32 vFFR values agreed with positive or negative FFR. Positive vFFR values were seen in all 15 vessels with positive FFR. 3 vessels received a positive vFFR where FFR values were negative. Mean vFFR was 0.76 +/- 0.1 and mean FFR was 0.81 +/- 0.09. vFFR correlated significantly with FFR (R=0.777, p&amp;lt;0.001). vFFR demonstrated good diagnostic accuracy in discriminating "positive" (&amp;gt;0.8) and "negative" (≤0.8) FFR with an AUC of 0.758 (95% CI 0.61-0.91, p&amp;lt;0.01). Conclusion vFFR correlated significantly with FFR and all positive FFR values also received positive vFFR values. vFFR demonstrated good diagnostic accuracy in predicting a positive FFR result. Thus, these data support a strategy of using a negative vFFR to avoid further testing.Pearson correlation of vFFR to invFFRROC curve: vFFR predicting invFFR

Fractional Flow Reserve Implications for Clinical Decision Making in Coronary Artery Disease.

Fractional flow reserve (FFR) is regarded as the gold standard for assessing the functional significance of coronary artery lesions. However, its utilization in clinical practice remains limited. This study aims to determine whether FFR results can influence treatment decisions for coronary artery disease compared to visual assessments of angiographic images. We conducted a retrospective study involving 63 patients diagnosed with either chronic coronary syndrome (n = 39, 61.9%) or acute coronary syndrome (n = 24, 38.1%) who underwent an FFR assessment. Three experienced interventional cardiologists (>300 PCI procedures/year) reevaluated 105 ambiguous coronary lesions in these patients, blinded to the FFR results. The objective was to assess lesion significance and determine the treatment strategy based on a visual angiographic evaluation. The three operators reached concordant agreement (≥two operators) to perform PCI in 60 (57.1%) of the evaluated lesions based on the angiographic assessment. Of these, nine lesions (15%) were deemed functionally non-significant by FFR (FFR > 0.80). Conversely, they agreed to defer PCI in 45 (42.9%) lesions, but 4 lesions (8.9%) were found to be functionally significant (FFR ≤ 0.80) and required a re-evaluation for PCI. Visual-guided decision making by interventional cardiologists shows variability and does not always align with the functional significance of coronary lesions as determined by FFR. Incorporating FFR into routine decision making could enhance treatment accuracy and patient outcomes.

Long-term association of post stent fractional flow reserve with clinical events

Abstract Background Low fractional flow reserve (FFR) after percutaneous coronary intervention (PCI) is associated with procedural factors in the stented segment and residual disease in the non-stented segment. Even the prognostic value of post-PCI FFR has been reported, its long-term clinical relevance has not been thoroughly investigated. Purpose We sought to investigate the long-term prognostic value of post-PCI FFR and its relative significance on future events in stented and non-stented segments. Methods The International Post-PCI FFR extended registry (NCT04684043) followed the 2,200 patients who underwent PCI and measured post-PCI FFR between June 2011 and May 2018. The primary outcome was target vessel failure (TVF), a composite of cardiac death, target vessel myocardial infarction (TVMI), and target vessel revascularization (TVR) at 5 years. The secondary outcomes were a composite of cardiac death or TVMI at 5 years. Results The median value of post-PCI FFR of target vessels was 0.89 (IQR 0.84-0.93). The optimal cut-off value of post-PCI FFR for predicting TVF was 0.81, and that for predicting cardiac death or TVMI was 0.76, respectively. The cumulative incidence of TVF was significantly higher in the low post-PCI group (20.5%) than in the high post-PCI FFR group (10.3%) (adjusted hazard ratio [HR] 2.11, 95% confidence interval [CI] 1.56-2.86, p&amp;lt;0.001). The cumulative incidence of cardiac death or TVMI was also significantly higher in the low post-PCI FFR group (7.3%) than in the high post-PCI FFR group (3.2%) (adjusted HR 2.34, 95% CI 1.12-4.91, p=0.024). Landmark analysis at 2 years showed that the impact of post-PCI FFR on TVF was consistently found during the first 2 years (adjusted HR of low post-PCI FFR 2.22, 95% CI 1.54-3.21, p&amp;lt;0.001) and thereafter (adjusted HR of low post-PCI FFR 1.96, 95% CI 1.14-3.36, p&amp;lt;0.001). However, the impact of post-PCI FFR on cardiac death or TVMI was more significant after 2 years of follow-up (adjusted HR of low post-PCI FFR 2.01, 95% CI 0.66-6.11, p=0.217 for the first 2 years and adjusted HR of low-post PCI FFR 2.81, 95% CI 1.04-7.60, p=0.042). The cumulative incidence of TVR was 9.5% for 5 years, and 61.0% of TVRs occurred in the stented segment. However, the proportion of TVRs in the non-stented segment increased along with the decrease of post-PCI FFR (35.3% in post-PCI FFR more than 0.90, 34.1% in post-PCI FFR 0.81-0.90, 43.8% in post-PCI FFR 0.71-0.80, and 66.7% in post-PCI FFR 0.70 and less than 0.70, p-for trend&amp;lt;0.001). Conclusions The long-term outcome results of the Internation Post-PCI FFR Extended registry showed that the prognostic impact of post-PCI FFR on TVF was consistently found along with the follow-up. However, that of post-PCI FFR on cardiac death or TVMI was more prominent during the late period of follow-up. In addition, clinical event distribution was different according to post-PCI FFR values.

Discordance between quantitative coronary angiography and fractional flow reserve or intravascular ultrasound: a substudy of the FLAVOUR trial

Abstract Background Discrepancies between quantitative coronary angiography (QCA) and fractional flow reserve (FFR) or intravascular ultrasound (IVUS) are often observed in coronary lesions with intermediate stenosis. Objectives We investigated the impact of physiology- or intracoronary imaging-directed revascularization strategies on clinical outcomes in patients with discordant coronary lesions between QCA and FFR or IVUS. Methods This study was a post hoc analysis of the FLAVOUR study, an investigator-initiated, prospective, randomized, open-label, multinational trial performed at 18 sites in Korea and China. In the FLAVOUR study, 200 patients with ≥60% diameter stenosis (DS) deferred percutaneous coronary intervention (PCI) according to FFR &amp;gt; 0.8 (n=141) or a minimal lumen area &amp;gt; 3 mm2 or 3-4 mm2 with a plaque burden &amp;lt;70% on IVUS whereas 351 patients with &amp;lt;60% DS performed PCI according to positive FFR (n=118) or positive IVUS (n=233) results. The primary outcome was a patient-oriented composite outcome (POCO), a composite of death, myocardial infarction, or revascularization. Results The incidence of discordance was 28.1% in the FFR group and 32.4% in the IVUS group. At 24 months, among patients with ≥60% DS, the incidence of POCO was similar between FFR-guided and IVUS-guided deferral strategies (4.4% vs. 3.4%, p=0.757). Among patients with &amp;lt;60% DS, FFR-directed or IVUS-directed PCI did not differ in the POCO incidence (5.2% vs. 2.6%, p=0.207). However, FFR-guided PCI showed a higher incidence of periprocedural myocardial infarction than IVUS-guided PCI in &amp;lt;60% DS lesions (2.6% vs. 0.0%, p=0.014). Conclusions In patients with discordant intermediate stenosis between QCA and FFR or IVUS, physiology- and imaging-directed revascularization strategies are comparable concerning POCO at 24 months.

Abstract 12127: Diagnostic Performance of Fractional Flow Reserve, Instantaneous Wave-Free Ratio and Quantitative Flow Ratio, on the Same Patient and Procedure

Introduction: Contemporary percutaneous coronary intervention (PCI) seeks precision and physiological assessment of coronary artery stenosis. Fractional Flow Reserve (FFR) is currently the gold standard for lesion physiology assessment; however, it's invasive and expensive. Other modalities, such as Quantitative Flow Ratio (QFR) and Instantaneous Wave-Free Ratio (iFR), can also determine the functional repercussion of coronary stenosis less invasively. Hypothesis: The results of FFR, iFR, and QFR of the same lesion, obtained during the same PCI, demonstrate the significant diagnostic capability of iFR and QFR, compared with FFR. Methods: Retrospective and unicentric study with stable chronic heart disease patients who underwent PCI. For every angiographic lesion, FFR, iFR and QFR were realized during the PCI. QFR was performed by an X-ray technician, blinded to the FFR and iFR results. A descriptive analysis was performed, as well as a correlation between the three measurements with Pearson’s r, chi-square, and ROC curve; and Bland-Altman plot for the results of FFR and QFR. Results: Thirty-six lesions of 27 patients were analyzed. For FFR, stenosis was considered significant when the result was &lt;0.80, obtaining 17 lesions (52%) as significant; for iFR, it was &lt;0.89, obtaining 14 significant lesions (38%); and for QFR, it was &lt;0.85, resulting in 19 (52%) significant lesions. Considering that FFR is the actual gold standard, a ROC curve was used to analyze QFR, were the best cutoff value was 0.88 with a sensitivity of 88% and specificity of 64% (AUC of 0.86, 95% CI 0.736- 0.991, p&lt;0.001), while for iFR the best cutoff value was 0.90 with a sensitivity of 82% and specificity of 74% (AUC of 0.85, 95% CI 0.722-0.984, p&lt;0.001). Pearson’s r revealed a significant correlation between FFR-iFR (r=0.6, p&lt;0.001), FFR-QFR (r=0.58, p&lt;0.001), and QFR-iFR (r=0.62, p&lt;0.001). Bland-Altman plot showed no significant difference between the data obtained with FFR and QFR. Chi-square test determined (p&lt;0.001) that the three angiographic methods had a good correlation in determining whether a lesion was significant. Conclusion: The study demonstrated the significant diagnostic capability that the QFR and iFR methods have, when compared against the current gold standard FFR.

The Impact of Age on the Physiological Assessment of Borderline Coronary Stenoses.

Background and Objectives: Coronary angiography is the gold standard for diagnosing coronary artery disease (CAD). In the case of borderline changes, patients require further diagnosis through ischemia assessment via one of the recommended methods of invasive evaluation. This study aimed to assess whether clinical factors influence the risk of a positive result in invasive myocardial ischemia assessment and if these potential factors change with the patient's age and the consistency of ischemia assessment. Materials and Methods: Data were collected retrospectively on all consecutive patients hospitalized in the University Hospital in Krakow between 2020 and 2021, on whom physiological assessments of coronary circulation were performed. Patients were divided into two groups: patients aged 60 or younger and patients older than 60. Results: Despite the older patients having more risk factors for CAD, their physiological assessment results of borderline lesions were similar to those of the younger patients. Positive fractional flow reserve (FFR) assessments were obtained from almost 50% of vessels. In the younger patients, cigarette use and type 2 diabetes mellitus increased the risk of a positive FFR result by 3.5 and 2.5 times, respectively. In the older patients, male gender and peripheral vascular disease significantly increased the risk of a positive FFR by 2.5 and 2 times, respectively. Conclusions: Clinical characteristics of patients undergoing physiological assessment of borderline coronary stenosis varied significantly by age. Refining the definition of borderline lesions to include age, gender, and other factors may improve the identification of patients who would benefit from physiological assessment and coronary revascularization.

Prognostic Value of Coronary CT Angiography-derived Fractional Flow Reserve on 3-year Outcomes in Patients with Stable Angina.

Background The prognostic value of coronary CT angiography (CTA)-derived fractional flow reserve (FFR) beyond 1-year outcomes and in patients with high levels of coronary artery calcium (CAC) is uncertain. Purpose To assess the prognostic value of coronary CTA-derived FFR test results on 3-year clinical outcomes in patients with coronary stenosis and among a subgroup of patients with high levels of CAC. Materials and Methods This study represents a 3-year follow-up of patients with new-onset stable angina pectoris who were consecutively enrolled in the Assessing Diagnostic Value of Noninvasive CT-FFR in Coronary Care, known as ADVANCE (ClinicalTrials.gov: NCT02499679) registry, between December 2015 and October 2017 at three Danish sites. A high CAC was defined as an Agatston score of at least 400. A lesion-specific coronary CTA-derived FFR value of 2 cm with distal-to-stenosis value at or below 0.80 represented an abnormal test result. The primary end point was a composite of all-cause death and nonfatal spontaneous myocardial infarction. Event rates were estimated using the one-sample binomial model, and relative risk was compared between participants stratified by results of coronary CTA-derived FFR. Results This study included 900 participants: 523 participants with normal results (mean age, 64 years ± 9.6 [SD]; 318 male participants) and 377 with abnormal results from coronary CTA-derived FFR (mean age, 65 years ± 9.6; 264 male participants). The primary end point occurred in 11 of 523 (2.1%) and 25 of 377 (6.6%) participants with normal and abnormal coronary CTA-derived FFR results, respectively (relative risk, 3.1; 95% CI: 1.6, 6.3; P < .001). In participants with high CAC, the primary end point occurred in four of 182 (2.2%) and 19 of 212 (9.0%) participants with normal and abnormal coronary CTA-derived FFR results, respectively (relative risk, 4.1; 95% CI: 1.4, 11.8; P = .001). Conclusion In individuals with stable angina, a normal coronary CTA-derived FFR test result identified participants with a low 3-year risk of all-cause death or nonfatal spontaneous myocardial infarction, both in the overall cohort and in participants with high CAC scores. Clinical trial registration no. NCT02499679 Published under a CC BY 4.0 license. Supplemental material is available for this article. See also the editorial by Sinitsyn in this issue.

Midterm Clinical Outcomes for Deferred Coronary Revascularization on the Basis of Resting Full-Cycle Ratio and Fractional Flow Reserve Measurements

The midterm prognosis of patients with deferred revascularization based on resting full-cycle ratio (RFR) or fractional flow reserve (FFR) is not well established. We investigated the midterm clinical outcomes of 137 consecutive patients with deferred revascularization of 177 coronary arteries based on RFR and FFR. Patients were classified into 3 groups (concordant normal, concordant abnormal, discordant FFR and RFR), using known cutoffs for FFR (≤0.80) and RFR (≤0.89). All-cause mortality occurred in 9 (6.6%) and major adverse cardiac events (MACEs) in 16 patients (11.7%). Concordant abnormal, age, body mass index (BMI), and current or history of cancer were associated with increased risks of all-cause mortality. In a multivariable model, current or history of cancer was significantly associated with all-cause death (hazard ratio [HR] 6.8, p=0.02). Concordant abnormal, current or history of cancer, BMI, and left ventricular ejection fraction were associated with increased risk of MACE, and all predictors correlated significantly with MACE (abnormal concordance: HR 4.2, p=0.043; current or history of cancer: HR 4.0, p=0.047; BMI: HR 0.8, p=0.020; left ventricular ejection fraction: HR 0.9, p=0.017). Although these results support performing percutaneous coronary intervention according to evidence-based RFR or FFR thresholds, deferred lesions with discordant FFR and RFR results were not associated with worse prognosis.

Benefits of the selective invasive strategy guided by CTA andCTA-derived fractional flow reserve in patients with coronary artery disease.

Coronary computed tomography angiography (CTA) has high diagnostic accuracy in ruling out significant stenosis of coronary arteries. The additional use of CTA- derived fractional flow reserve (FFR) further enhances diagnostic utility of coronary CTA. Some patients interrogated non-invasively have diseased coronary arteries and undergo further diagnostic testing, including invasive coronary angiography (ICA). Patients with one-vessel disease may benefit from invasive interrogation limited to the diseased vessel only. We analyzed the impact of a "diseased-vessel-only" selective invasive diagnostic approach in 100 patients undergoing ICA following coronary CTA (and CT-FFR) as compared to the traditional "full ICA" approach. We aimed to compare contrast volume and radiation dose used during ICA in both scenarios, seeking potential benefits for the patient in reducing those values by the "dis-eased-vessel-only" approach. Sensitivity, specificity, positive predictive value, and negative predictive value of CTA in prediction of subsequent revascularization were 96%, 75%, 51%, and 99%, respectively, and for CT-FFR 90%, 90%, 69%, and 97%, respectively. Using CTA as a method to guide ICA would reduce contrast volume and estimated radiation dose (ED) by 35% and 42.0%, respectively (P <0.0001 for both). Taking into consideration CT-FFR results, contrast volume would be reduced by 57% and ED by 69% (P <0.0001 for both). These real-world data support the concept that vessels with <50% diameter stenosis on quantitative computed tomography and with hemodynamically insignificant CTA-derived FFR result may be omitted during ICA. Such an approach would result in substantial reductions in con-trast media volume used, as well as patients' exposure to radiation during ICA, while not leading to misdiagnoses.

Insufficient adenosine-induced hyperemia is a major determinant of discordance between non-hyperemic pressure ratio and fractional flow reserve

Adenosine occasionally overestimates fractional flow reserve (FFR) values (i.e., insufficient adenosine-induced hyperemia), leading to low non-hyperemic pressure ratios (NHPR)–high FFR discordance. We investigated the impact of insufficient adenosine-induced hyperemia on NHPR–FFR discordance and the reclassification of functional significance. We measured resting distal-to-aortic pressure ratio (Pd/Pa) and FFR by using adenosine (FFRADN) and papaverine (FFRPAP) in 326 patients (326 vessels). FFRADN overestimation was calculated as FFRADN − FFRPAP. We explored determinants of low Pd/Pa − high FFRADN discordance (Pd/Pa ≤ 0.92 and FFRADN > 0.80) versus high Pd/Pa − low FFRADN discordance (Pd/Pa > 0.92 and FFRADN ≤ 0.80). Reclassification of functional significance was defined as FFRADN > 0.80 and FFRPAP ≤ 0.80. Multivariable analysis identified FFRADN overestimation (p = 0.002) and heart rate at baseline (p = 0.048) as independent determinants of the low Pd/Pa–high FFRADN discordance. In the low Pd/Pa–high FFRADN group (n = 26), papaverine produced a further decline in the FFR value in 21 vessels (81%) compared with FFRADN, and the reclassification was observed in 17 vessels (65%). Insufficient adenosine-induced hyperemia is a major determinant of the low resting Pd/Pa–high FFR discordance. Physicians should bear in mind that the presence of low NHPR–high FFR discordance may indicate a false-negative FFR result.

The impact of coronary microvascular dysfunction on the discordance between fractional flow reserve and resting full-cycle ratio in patients with chronic coronary syndromes.

BackgroundResting full-cycle ratio (RFR) is an alternative to fractional flow reserve (FFR) for the evaluation of borderline coronary artery lesions. Although FFR and RFR results are discordant in some cases, factors associated with the discordance remain unclear. The role of coronary microvascular dysfunction (CMD) is discussed as a potential mechanism to explain these discrepancies.AimThe study aimed to assess concordance between RFR and FFR in a real-life cohort from a high-volume center regarding the role of CMD.MethodsConsecutive patients with borderline coronary lesions undergoing coronary functional testing for chronic coronary syndromes were included in the study. Measurements of RFR and FFR were performed alongside additional coronary flow reserve (CFR), resistance reserve ratio (RRR), and an index of microcirculatory resistance (IMR) measurements. CMD was defined according to the current guideline by either IMR ≥25 or CFR ≤2.0 in vessels with no significant stenosis.ResultsMeasurements were performed in 157 coronary arteries, in 101 patients, with a median age of 66 y., 74% male, with prior history of arterial hypertension (96%), dyslipidaemia (91%), and diabetes (40%). The median value of vessel diameter stenosis was 45% according to QCA.Overall, FFR and RFR values were significantly correlated (r = 0.66, p < 0.001), where positive FFR/negative RFR and negative FFR/positive RFR were observed in 6 (3.8%) and 38 (24.2%) of 157 vessels. The RFR/FFR discrepancy was present in 44 (28%) of measurements. CMD was confirmed in 28 (64%) of vessels with discrepant RFR/FFR and in 46 (41%) of vessels with concordant results (p = 0.01). In discordant RFR/FFR vessels, as compared to concordant ones, significantly lower values of CFR [median 1.95 (IQR: 1.37, 2.30) vs. 2.10 (IQR: 1.50, 3.00), p = 0.030] and RRR [median 2.50 (IQR: 1.60, 3.10) vs. 2.90 IQR (1.90, 3.90), p = 0.048] were observed.Main predictors of RFR/FFR discrepancy in a univariate regression analysis were: higher age of patients [OR = 1.06 (1.01; 1.10), p = 0.010], presence of CMD [OR = 2.51 (1.23; 5.25), p = 0.012], lower CFR [OR = 1.64 (1.12; 2.56), p = 0.018], and lower RRR values [OR = 1.35 (95% CI: 1.03; 1.83), p = 0.038].ConclusionIn discrepant RFR/FFR vessels, CMD is more prevalent than in concordant RFR/FFR measurements, which can be driven by lower CFR or RRR values. Further research is needed to confirm this observation.

Coronary Computed Tomography Angiography-derived Fractional Flow Reserve: An Expert Consensus Document of Chinese Society of Radiology.

Invasive fractional flow reserve (FFR) measured by a pressure wire is a reference standard for evaluating functional stenosis in coronary artery disease. Coronary computed tomography angiography-derived fractional flow reserve (CT-FFR) uses advanced computational analysis methods to noninvasively obtain FFR results from a single conventional coronary computed tomography angiography data to evaluate the hemodynamic significance of coronary artery disease. More and more evidence has found good correlation between the results of noninvasive CT-FFR and invasive FFR. CT-FFR has proven its potential in optimizing patient management, improving risk stratification and prognosis, and reducing total health care costs. However, there is still a lack of standardized interpretation of CT-FFR technology in real-world clinical settings. This expert consensus introduces the principle, workflow, and interpretation of CT-FFR; summarizes the state-of-the-art application of CT-FFR; and provides suggestions and recommendations for the application of CT-FFR with the aim of promoting the standardized application of CT-FFR in clinical practice.

The impact of deep learning reconstruction on image quality and coronary CT angiography-derived fractional flow reserve values.

To explore the impact of deep learning reconstruction (DLR) on image quality and machine learning-based coronary CT angiography (CTA)-derived fractional flow reserve (CT-FFRML) values. Thirty-three consecutive patients with known or suspected coronary artery disease who underwent coronary CTA and subsequent invasive coronary angiography were enrolled. DLR was compared with filtered back projection (FBP), statistical-based iterative reconstruction (SBIR), model-based iterative reconstruction (MBIR) Cardiac, and MBIR Cardiac sharp for objective image qualities of coronary CTA. Invasive fractional flow reserve (FFR) and quantitative flow ratio (QFR) were used as the reference standards. The diagnostic performances of different reconstruction approach-based CT-FFRML were calculated. A total of 182 lesions in 33 patients were enrolled for analysis. The image quality of DLR was superior to the others. There were no significant differences in the CT-FFRML values among these five approaches (all p > 0.05). Of the 182 lesions, 17 had invasive FFR results, and 70 had QFR results. Using FFR as a reference, MBIR Cardiac, MBIR Cardiac sharp, and DLR achieved equal diagnostic performance, slightly higher than the other reconstruction approaches (MBIR Cardiac, MBIR Cardiac sharp, and DLR: AUC = 0.82, FBP and AIDR: AUC = 0.78, all p > 0.05). Using QFR as a reference, the AUCs of FBP, SBIR, MBIR Cardiac, MBIR Cardiac sharp, and DLR were 0.83, 0.81, 0.86, 0.84, and 0.83, respectively (all p > 0.05). Our study showed that the DLR algorithm improved image quality, but there were no significant differences in the CT-FFRML values and diagnostic performance among different reconstruction approaches. • Deep learning-based image reconstruction (DLR) improves the image quality of coronary CTA. • CT-FFRML values and diagnostic performance of DLR revealed no significant differences compared to other reconstruction approaches.

Factors associated with discordance between fractional flow reserve and resting full-cycle ratio

BackgroundResting full-cycle ratio (RFR), a non-hyperemic pressure ratio, is alternative to fractional flow reserve (FFR) for the evaluation of coronary artery stenoses. Although FFR and RFR results are often discordant using the cut-off values (0.80 and 0.89), factors associated with the discordance are unclear. The aim of this study was to explore factors related to the discordant results. MethodsWe performed FFR and RFR measurements in a total of 408 vessels with intermediate coronary artery stenosis in 277 patients. Positive FFR and RFR were defined based on the cut-off values of 0.80 and 0.89. The discordance was determined as positive FFR and negative RFR (FFR ≤0.80 and RFR >0.89) or negative FFR and positive RFR (FFR >0.80 and RFR ≤0.89). ResultsOverall, FFR and RFR were significantly correlated (r = 0.76, p < 0.001), while positive FFR and negative RFR and negative FFR and positive RFR were observed in 44 (10.8%) and 45 (11.0%) of 408 vessels, respectively. Smaller body surface area, diabetes, chronic kidney disease including hemodialysis, severe aortic stenosis, higher E/e', and lower left ventricular ejection fraction on echocardiography, and lower hemoglobin and higher brain natriuretic peptide levels were identified as factors associated with the negative FFR and positive RFR discordance. ConclusionsDiscordant results between FFR and RFR were often found in more than 20% of vessels with intermediate coronary stenosis. Clinical characteristics such as renal function, heart failure, and anemia may be considered in clinical decision-making when using FFR and RFR.

Efficacy of fractional flow reserve measurement in the assessment of stenotic lesions of coronary artery

Context: The decision to perform an intervention on a narrowed coronary artery depends on the ischemia caused by the stenosis. The indication for intervention usually applies to cases with ≥70% stenosis of vascular diameter because of the risk of myocardial ischemia. Aims: To define the efficacy of fractional flow reserve (FFR) measurement in the evaluation of coronary artery stenosis. Methods: This prospective study was conducted on patients with intermediate coronary artery stenosis who underwent quantitative coronary angiography after coronary computed tomography angiography. Results: The study population consisted of 46 men and 26 women with a mean age of 66.0 ± 12.9 years. FFR was significantly correlated with the grade of angina pectoris (r = – 0.387; p&lt;0.01) and showed a negative correlation with percentage diameter stenosis (r = – 0.241, p&lt;0.05) and a positive correlation with the minimal lumen diameter (MLD; r = 0.377, p&lt;0.05). The cut-off value to predict positive FFR was &gt;55.62% diameter stenosis and MLD ≤ 1.08 mm. FFR ≤ 0.80 indicating intervention and FFR &gt; 0.80 indicating medical therapy were observed in 56.9% and 43.1% of the cases, respectively. No major cardiac complications occurred during 12 months of follow-up in both groups. Conclusions: FFR measurements for intermediate stenosis of the coronary artery should be used to evaluate the possibility of myocardial ischaemia. If FFR is not available, a cut-off point of &gt;55.62% diameter stenosis or MLD ≤ 1.08 mm can be used to predict the FFR results.

Significance of Guide Catheter Disengagement During Fractional Flow Reserve (FFR) Measurements Following Intracoronary Adenosine

FFR is well established for physiological assessment of 50–70% stenosis in single or multivessel disease and can guide revascularisation decisions. Many factors affect the FFR result, including guide catheter disengagement.

Significance of Guide Catheter Disengagement During Fractional Flow Reserve (FFR) Measurements Following Intracoronary Adenosine

FFR is well established for physiological assessment of 50–70% stenosis in single or multivessel disease and can guide revascularisation decisions. Many factors affect the FFR result, including guide catheter disengagement.

Fractional flow reserve in patients with type 1 or type 2 non-ST elevation acute myocardial infarction.

We assessed a combined strategy of fractional flow reserve (FFR) plus angiography in stratifying cardiovascular risk in patients with type 1 myocardial infarction (T1MI) or type 2 (T2MI) non-ST elevation acute myocardial infarction (NSTEMI). A cohort of 150 NSTEMI patients were prospectively studied. Clinical and angiographic features guided the identification of T1MI vs T2MI and the treatment of culprit lesions. Subsequently, T1MI patients underwent FFR evaluation of nonculprit stenoses. In T2MI patients all angiographically significant stenoses were evaluated by FFR. FFR < 0.80 was an indication for revascularization. Based on FFR results, two groups were compared: patients with all lesions ≥0.80 ('defer' group, n = 87) and those with at least one lesion <0.80 ('perform' group, n = 63). The primary end point was the composite of all-cause death, nonfatal MI and unplanned coronary revascularization. Median clinical follow-up was of 35 months (interquartile range 14-44). Primary end-point rates in the 'defer' and 'perform' groups were 14.5% and 30.0% at 12 months and 28% and 46% at 36 months, respectively (log-rank test: at 1 year, P = 0.007; at the end of follow-up P = 0.014). On multivariable analysis, chronic kidney disease (HR 3.50, 95% CI: 1.89-6.46, P = 0.0001) and FFR group ('perform' vs 'defer': HR 1.75 95% CI: 1.01-3.04, P = 0.046) were independent predictors of adverse events. In NSTEMI patients, our results indicated that FFR combined with angiography allowed the treatment of nonfunctional significant lesions to be safely deferred and patient cardiovascular risk to be identified.

The Hemodynamic Mechanism of FFR-Guided Coronary Artery Bypass Grafting.

Clinically, fractional flow reserve (FFR)-guided coronary artery bypass grafting (CABG) is more effective than CABG guided by coronary angiography alone. However, no scholars have explained the mechanism from the perspective of hemodynamics. Two patients were clinically selected; their angiography showed 70% coronary stenosis, and the FFRs were 0.7 (patient 1) and 0.95 (patient 2). The FFR non-invasive computational model of the two patients was constructed by a 0–3D coupled multiscaled model, in order to verify that the model can accurately calculate the FFR results. Virtual bypass surgery was performed on these two stenoses, and a CABG multiscaled model was constructed. The flow rate of the graft and the stenosis coronary artery, as well as the wall shear stress (WSS) and the oscillatory shear index (OSI) in the graft were calculated. The non-invasive calculation results of FFR are 0.67 and 0.91, which are close to the clinical results, which proves that our model is accurate. According to the CABG model, the flow ratios of the stenosis coronary artery to the graft of patient 1 and patient 2 were 0.12 and 0.42, respectively. The time-average wall shear stress (TAWSS) results of patient 1 and patient 2 grafts were 2.09 and 2.16 Pa, respectively, and WSS showed uniform distribution on the grafts. The OSI results of patients 1 and 2 grafts were 0.0375 and 0.1264, respectively, and a significantly high OSI region appeared at the anastomosis of patient 2. The FFR value of the stenosis should be considered when performing bypass surgery. When the stenosis of high FFR values is grafted, a high OSI region is created at the graft, especially at the anastomosis. In the long term, this can cause anastomotic blockage and graft failure.